The present invention relates to an apparatus and method for making a shaped-spring assembly for use in a magnetic head-to-media backer. More specifically, the present invention relates to an apparatus and method for making a shaped-spring assembly which involves the use of a shaped spring forming unit and a shaped spring storing and loading magazine.
Shaped-spring assemblies have been used in a number of electrical and mechanical devices such as cameras, tape decks, sound recording devices, and automated materials handling machinery. These shaped-spring assemblies are commonly called bubble-spring assemblies and are employed in situations that require a constant load with the ability to accommodate large spacial displacements. A typical bubble-spring assembly provides a restraining force against a moving piece of a magnetic section of a film, so that the film is held against a recording head under constant pressure.
A bubble-spring assembly typically includes a cavity that comprises a block and the bubble spring. The cavity includes a shaped-hollow cavity formed through the block and the bubble spring is typically small and thin. Due to the size of the spring, delicate handling of the spring is required. The bubble spring is positioned within the cavity to form a convex or arched portion that extends beyond the dimension of the cavity block. In this manner, the bubble spring is placed under tension and will thereby provide a spring force against an article, such as film, that has displaced the spring into the cavity. Prior to shaping and insertion into the cavity, the bubble spring is a flat elongated piece of thin material, typically metal, and commonly referred to as a spring blank. This type of bubble spring assembly is disclosed in, for example, U.S. Pat. Nos. 5,274,522 and 5,531,008.
In a conventional APS film strip, there is a magnetic layer that provides a way to read and/or write data. The above-mentioned U.S. Pat. No. 5,274,522 as noted above, discloses a bubble spring load pad which is a film backer pad used for urging the film base to a magnetic head. This backer pad (also known as a bubble spring assembly) includes a cavity and the bubble spring. After extended use of the assembly including the bubble spring, it has been found that the spring needs to be routinely replaced. This is due to the constant urging of the bubble spring against the magnetic layer of the film. Due to cost, it is not economically feasible to replace both the cavity and the bubble spring each time the spring needs to be replaced. It is preferred to use the existing cavity and install a new spring. However, as noted above, the springs tend to be small and thin, and thus very difficult to accurately replace within a small cavity without adversely effecting the spring characteristics of the spring. Also, in reloading bubble springs within a cavity, manufactures and/or consumers may use springs from manufactures that may provide poor spring performance due to inferior material and/or manufacturing methods.
A method of replacing a spring as disclosed in the above-mentioned U.S. Pat. No. 5,531,008 is complex and has a fair amount of cost and usage difficulty associated with it. The apparatus as disclosed in U.S. Pat. No. 5,531,008 also only supplies one spring at a time. Further, the method of spring installation as disclosed in the U.S. Pat. No. 5,531,008 causes the leading half of the spring to be fatigued during spring installation by the way the leading edge of the spring gets forced into, then around, a tight radius. This causes the leading half of the spring to be fatigued. This may cause the spring load to be lower in head load after spring installation than is desired. That is, the film has what is called an anticlastic effect (edge curl) under the edge of the film on/or close to the magnetic head track signal location. Under certain situations such as lower humidity and/or core set film, a lower gram load could limit the springs ability to provide the needed force on the outside track location to provide a high enough force to obtain consistent read/write signal processing.
The loading or replacement of springs needs to be done in a manner which does not result in too large or too low of a spring force, since a large spring force would tend to damage the film or article that the spring rides against, and a low spring force would not provide enough of a force to urge the spring against, for example, a magnetic head.
The present invention provides for an improved method and apparatus for making a bubble spring (hereinafter referred to as a shaped-spring) assembly. The method and apparatus of the present invention utilizes a novel shaped-spring magazine arrangement as well as a novel spring forming unit.
The present invention provides for a mechanism which reduces or eliminates the necessity of installing undesired springs from manufactures that may use unapproved springs which can cause poor performance. This is because the present invention provides for a magazine that can be pre-loaded at a controlled location.
The present invention provides for a shaped spring magazine arrangement for making a shaped spring assembly. The shaped spring magazine arrangement comprises a base member having a first section adapted to hold a row of shaped springs and a second section adapted to hold a shaped spring cavity. A first shaped spring in the row of shaped springs is located at a first end of the first section adjacent to the second section, and a last shaped spring of the row of shaped springs is located at a second end of the first section opposite to the first end. The magazine arrangement further comprises a plurality of spacer members provided on the first section of the base member so as to be positioned between the shaped springs in the row of shaped springs; and a pusher member adapted to be inserted into the second end of the first section so as to push against the last shaped spring of the row of shaped springs, and cause the first shaped spring of the row of shaped springs to be inserted into a shaped spring cavity located at the second section.
The present invention further relates to a method of making a shaped-spring assembly. The method comprises the steps of alternatively providing shaped springs and spacer members on a first section of a base member so as to create a row of the shaped springs with the spacer members located between the shaped springs; providing a shaped spring cavity on a second section of the base member; and pushing a first shaped spring of the row of shaped springs which is furthest from the shaped-spring cavity, so as to urge a second shaped spring from the row of shape springs which is closest to the shaped spring cavity out of the first section of the base member and into the shaped spring cavity so as to form a shaped spring assembly.
The present invention further relates to a shaped spring magazine arrangement for making a shaped-spring assembly that comprises a base member having a first part adapted to hold at least one shaped spring and a second part adapted to hold a shaped spring cavity.
The present invention further relates to a method of making a shaped spring assembly which comprises the steps of positioning shaped springs in a row on a first part of a base member; placing an empty shaped-spring cavity on a second part of the base member; and loading one of the shaped springs in the row of shaped springs into the empty shaped-spring cavity.
The present invention further relates to a spring shaping tool for forming shaped springs. The spring shaping tool comprises a housing assembly having a longitudinal bore adapted to hold a mandrel therein, and a recess which extends in a direction transverse to the longitudinal bore; a spring former sized to be slidably insertable in said recess, the spring former comprising a slot which is sized to receive a spring blank and an opening extending from the slot. The spring former is slidable in the recess from at least a first position to a second position in which the opening surrounds the mandrel, such that a sliding of the spring former to the second position causes a spring blank positioned in the slot to be partially wrapped around the mandrel and extend into the opening, to thereby form a shaped spring.
The present invention further relates to a method of shaping a spring blank to form a shaped spring which comprises the steps of placing a spring blank in a slot of a spring former which is adapted to fit within a recess of a housing assembly, with the spring former having an opening which extends from the slot; and pressing the spring former having the spring blank therein in the recess of the housing assembly. The housing assembly has a longitudinal bore with a mandrel positioned therein that extends through the recess, such that the spring blank in the slot of the spring former partially wraps around the mandrel and extends into the opening, to thereby form a shaped spring.
The present invention further relates to a spring forming and loading assembly which comprises a shaping tool for shaping spring blanks to form shaped springs; and a shaped spring magazine for storing shaped springs formed by the shaping tool as a row of shaped springs, and loading the shaped springs into an empty shaped spring cavity.
The present invention further relates to a method of forming, storing and loading shaped springs to form shaped spring assemblies, which comprises the steps of (a) placing a spring blank in a slot of a spring forming member, with the spring forming member having an opening which extends from the slot; (b) pressing the spring forming member having the spring blank therein within a recess of a housing assembly, with the housing assembly having a bore with a mandrel positioned therein that extends through the recess, such that the spring blank in the slot of the spring forming member partially wraps around the mandrel and extends into the opening, to thereby form a shaped spring; (c) transferring the shaped spring to a magazine; (d) positioning the shaped spring on a first part of the magazine; (e) repeating the steps (a)-(d) until a desired number of shaped springs are formed and positioned in a row on the first part of the magazine; (f) placing an empty shaped spring cavity on a second part of the magazine; and (g) pushing one end of the row of shaped springs so as to load one of the shaped springs in the row of shaped springs into the empty shaped spring cavity.
Advantages of the method and apparatus of the present invention as described above is that it permits multiple shaped springs to be loaded one at a time by way of a storage method, and facilitates the storage of a multitude of springs for installation purposes.
Further, the method and apparatus of the present invention permits the loading of a magazine to be controlled at a select location. As an option, the magazine that is preloaded with shaped springs can be supplied to a field site for easy, correct spring installation capabilities. This allows the customer (end user) to have a steady supply of shaped springs available for quick replacement options, and permits the supply of shaped springs to be under a controlled environment by separating a spring forming function from spring storing and loading functions.
Further, a higher average installation load is realized by not fatiguing the leading edge of the spring installation.
Also, the present invention provides for a low cost and easy option for replacing springs since an end user could maintain a supply of magazines which are pre-loaded with shaped springs at a factory on site.
The method and apparatus of the present invention also facilitates field repairs by eliminating the need to send a cavity back to a manufacturer for repair.